MOSCOW, FEB. 8 -- Soviet leader Mikhail Gorbachev today offered the first specific date for a troop withdrawal from Afghanistan, saying the Kremlin could begin a pullout May 15 and complete it within 10 months, if a settlement is reached by mid-March.

The statement, released by the official news agency, Tass, offered concessions from earlier Soviet positions. It cut the proposed pullout schedule by two months and met U.S. objections by agreeing to remove a large number of troops in the early stages of a pullout, and continue the withdrawal regardless of whether the Afghans manage to agree on an interim government.

Gorbachev's surprise announcement came amid intensive talks aimed at ending the eight-year Soviet role in Afghanistan and was seen here as the most convincing signal yet that Moscow is determined to begin a troop pullout this year.

The statement was widely viewed here as a bid to overcome the differences among the negotiating parties, which are considerable, according to western specialists on the war.

By announcing a Soviet readiness to start the withdrawal of its estimated 115,000 to 120,000 troops in May, Gorbachev appeared to be putting pressure on Afghan and Pakistani negotiators and their U.N. mediator, who are expected to convene in Geneva before the end of this month for a crucial round of talks.

{U.N. Undersecretary General Diego Cordovez, who shuttled between the Pakistani and Afghan capitals today, said on Pakistani television that the negotiation is "slow, but moving with enormous difficulties toward its conclusion," The Associated Press reported. A senior Pakistani official said, "The fact that the Cordovez shuttle has been going on for 19 days shows a movement forward."}

Soviet citizens and western diplomats here reacted favorably to the news.

The Soviet Union invaded Afghanistan in December 1979 to prop up an indigenous communist regime that had taken power in a coup. The regime had sparked a civil war with hardline Marxist policies that inflamed the traditional, Moslem population.

The United States and Arab nations began aiding the Afghan mujaheddin, or guerrilla "holy warriors," sending arms through Pakistan, where the guerrillas and an estimated 2 million to 3 million refugees take sanctuary. Last year, the United States gave an estimated $600 million in arms to the mujaheddin.

The Reagan administration and the Kremlin have agreed to guarantee an agreement reached by Cordovez in the nearly six-year-old Geneva talks. The accord provides for a troop pullout, cessation of outside aid to the mujaheddin and the return of refugees.

In his announcement, which was read on the Soviet evening news program, Vremya, Gorbachev said: "Seeking to facilitate a speedy and successful conclusion of the Geneva talks between Afghanistan and Pakistan, the Soviet government and the Republic of Afghanistan have agreed to set a specific date for withdrawal of Soviet troops -- May 15, 1988 -- and to complete their withdrawal within 10 months."

"The date is set based on the assumption that agreements on the settlement would be signed no later than March 15, 1988, and that, accordingly, they would enter into force simultaneously two months after that," Gorbachev added.

Najibullah, in a statement read on television in Kabul and released by Tass, echoed Gorbachev's announcement but hinted that major snags were still left to be settled at the peace talks, expected to start later this month.

"If some governments and certain politicians take a stand directed at postponing the signing of the Geneva agreements under any pretext," Najibullah was quoted as saying, "this will be added proof of their desire to preserve tension in the region."

Gorbachev's statement, more conciliatory in tone than Najibullah's, included a concession to the U.S. demandthat the bulk of Soviet forces be pulled out early in the process to preclude last minute flare-ups in fighting.

"Recently, another question was raised, whether the phasing of Soviet troop withdrawals could be arranged in such a way as to withdraw, during the first phase already, a greater portion of the contingent. Well, that too could be done. The Afghan leadership and we agree to it."

In another concession, Gorbachev formally dropped any link between the troop pullout and the success of Najibullah's policy of national reconciliation. "We are convinced that {the withdrawal} is not . . . linked with the completion of efforts to set up a new, coalition government in Afghanistan," he said.

While giving the Afghan peace talks a push forward, Gorbachev emphasized that settlement of the war is far from accomplished.

Even though the conditions for a settlement exist, the Soviet leader said, "that, of course, does not mean that no one could now obstruct the settlement, or push the talks backwards." He also reiterated the Soviet position that "the withdrawal of troops is, quite naturally, linked with precluding interference in Afghanistan's internal affairs: prerequisites for that have now been created to mutual satisfaction."

One possible obstacle to a settlement is the recent refusal of Pakistan, a key negotiating partner, to sign an agreement with Najibullah's government in Kabul. President Mohammed Zia ul-Haq adopted that position in an interview last month, out of what was interpreted as concern that the retention of Najibullah in power would discourage Afghan refugees in Pakistan from returning home.

Although Soviet officials here have hinted at some disagreements between Moscow and the Afghan government, there has been no indication that Najibullah will step down to smooth the way to a conclusion of the war.

Another possible subject of disagreement is the timetable for withdrawal. In the past, Pakistan has favored an eight-month period, two months less than the timetable mentioned by Gorbachev today.

Another unsettled issue is the question of a peacekeeping force and the Soviet role after a pullout, particularly in the case of a bloodbath following the troop withdrawal.